A 3GPP (3-rd Generation Partnership Project) mobile communication system based on a WCDMA (Wideband Code Division Multiple Access) radio access technology has been widely spread all over the world. An HSDPA (High Speed Downlink Packet Access) which can be defined as a first evolution step of the WCDMA provides a radio access technology having a high competitive power in a mid-term future for the 3GPP. However, since requirements and expectations of users and providers have increased more and more and competitive development of the radio access technology has been made more and more, a new technological evolution of the 3GPP is required to enhance a high competitive power in the future.
The 3GPP entered into a project called “Evolved UTRA and UTRAN” from the end of 2004 for the purpose of development of a radio transmission technology which can provide a high-quality service and reduce cost. The project of 3G long term evolution (hereinafter, referred to as LTE) aims at expansion of a coverage, improvement of system capacity, decrease in cost of users and providers and improvement in service quality. The 3G LTE defines as high-level requirements decrease in cost per bit, enhancement in service availability, flexible utilization of frequency bands, open interface with a simple structure and appropriate power consumption of by user equipments.
In any communication system, data can be lost in a physical channel. With the development of technologies, the probability that data are not transmitted well from a transmitter to a receiver in the physical channel is lowered, but does not disappear completely. Particularly, in case of user equipments spaced apart from a base station, the data loss rate is high. Important signaling data or control signals need be subjected to more special management for the purpose of reliability of the communication systems.
One of techniques used to reduce the loss of data is an ARQ (Automatic Repeat Request) method. Generally, the ARQ method is performed by a high-level layer. Lower-level layers perform HARQ (Hybrid ARQ), thereby reducing the loss of data.
The HARQ uses a FEC (Forward Error Correction) and the ARQ together to correct an error of data by the use of the FEC and to retransmit the data by the use of the ARQ.
When a receiver fails to receive data at the time of retransmission, the reception failure should be rapidly reported to a transmitter. This is because it is possible to reduce the time for correction of an error and the time for solving an obstacle to data transmission by allowing the transmitter to rapidly recognize the data reception failure. As the transmitter recognizes more rapidly the reception failure, the time for retransmission is more reduced.